USB relay for roll-off roof winch

[Rallemikken]

My roof is operated by a slightly modded 220V two-way winch, and I'm planning to let Ekos pull the roof over the rig when the nights schedules are finished. I've mounted stop switches in both ends, so it's just a matter of  setting on current for a limited time, once it reach the end it switches off itself.

I've taken a look at these:    https://www.kmtronic.com/usb-relays.html

Looks like these can be operated by a single bash-script (I'm on linux). I might opt for the boxed four channel, maybe the eight. Might come handy later. Am I missing something? Anyone else tried these?

[Skipper Billy]

I use the ethernet version and it works a treat. The GUI wont win any awards but it has been totally reliable.

[Rallemikken]

Short update: Opted for the boxed 4-way USB relay, installed and tested. Some remarks, all this is done on Linux Mint 20.3:

* This version does not need any power supply, but be sure your USB-port delivers enough current. With all relays closed, it pulls some amps. I've plugged it into a USB-hub with it's own supply.

* It might conflict with any other equipment connected with a USB-to-serial plug, my HEQ5 for my part; it's connected with a EQDirRJ45 cable. To fix this, we must give the box it's own shortcut in /dev. This is done by writing a udev-rule, and reboot. Just like in Windoze.

* This box and my EQDir-cable uses the same chipset. [removed word]. Yours might not, but better safe than sorry. Unplug everything, apart from the box from KMTronic, and reboot.

* Run this in the shell:
udevadm info -a -n /dev/ttyUSB0 | grep '{serial}' | head -n1
You maybe get this response:
    ATTRS{serial}=="AB0LB2GY"

* Then we write our udev-rule. Make a file named /lib/udev/rules.d/99-observatory.rules This must be done as root, or via sudo.
This is how mine turned out in the end:

Line 1: # KMTronic box for takmotor (roofmotor)
Line 2: # SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="AB0LB2GY", MODE="0666", SYMLINK+="takmotor"
Line 3: # SUBSYSTEMS=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="AB0LB2GY", MODE="0666", SYMLINK+="takmotor"
Line 4: SUBSYSTEM=="tty", ACTION=="add", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="AB0LB2GY", MODE="0666", KERNEL=="ttyUSB*", SYMLINK="takmotor"

As you can see, I've fiddled a bit. The first three lines are commented out, line #2 and 3 are pure failures. The last line (line 4) did the trick. I suspect it was the last "S" in "SUBSYSTEMS", but we'll never know....   The  ACTION=="add" and KERNEL=="ttyUSB*" might play a role, anyway, putting them in don't seem to do any damage....

* So to the bash-file that is called after finished schedule in Ekos:

#!/bin/bash
#
#  1    FF 01 01    HEX     Turn ON relay 1
#  2    FF 02 01    HEX     Turn ON relay 2
#  3    FF 03 01    HEX     Turn ON relay 3
#  4    FF 04 01    HEX     Turn ON relay 4
#  9    FF 01 00    HEX     Turn OFF relay 1
# 10    FF 02 00    HEX     Turn OFF relay 2
# 11    FF 03 00    HEX     Turn OFF relay 3
# 12    FF 04 00    HEX     Turn OFF relay 4
#
echo -e "\xFF\x01\x01" > /dev/takmotor
echo -e "\xFF\x02\x01" > /dev/takmotor
sleep 30
echo -e "\xFF\x01\x00" > /dev/takmotor
echo -e "\xFF\x02\x00" > /dev/takmotor
sleep 3
exit

The 'sleep 30' gives the motor time to pull the roof all the way, it has a stop switch at the end of travel, timing is not cruzial for my part. The next two lines turns the relays back to their default, open configuration. I have a manual switch to OPEN the roof, and I don't want my USB-box to conflict with my manual switch in case I don't turn off my computer. The 'sleep 3' is just a precausion to let the computer finish the talk with the box. Next is 'init 0', but that's another story....

 

Edited September 17, 2022 by Rallemikken
Line numbering in "/lib/udev/rules.d/99-observatory.rules"

[old_eyes]

I use the velleman VM110N usb interface board with a non-name Chinese relay board. This works for me as my preferred automation software Voyager/Viking recognises and can control the Velleman board natively from its scripting language.

[Rallemikken]

6 hours ago, old_eyes said:

Voyager/Viking

Looks good, but I'm a Linux user. This was the simplest for me. With a fourway relay I also have the option to open the roof before the schedule, but i havn't implemented this yet. Feels safest to do it manually, must start the computer and switch on the DSLR and mount anyway.